So to be honest I’m not sold on this letting server share memory in the first place. It just sounds like an accident waiting to happen. In the case of SBS 2011 it has Exchange on there that loves to take all the RAM given to it and then release it as needed.

Exchange Server Memory Requirements and Recommendations

Some hypervisors have the ability to oversubscribe or dynamically adjust the amount of memory available to a specific guest machine based on the perceived utilization of memory in the guest machine as compared to the needs of other guest machines managed by the same hypervisor. This technology makes sense for workloads in which memory is needed for brief periods of time and then can be surrendered for other uses. However, it doesn’t make sense for workloads that are designed to use memory on an ongoing basis. Exchange, like many server applications with optimizations for performance that involve caching of data in memory, is susceptible to poor system performance and an unacceptable client experience if it doesn’t have full control over the memory allocated to the physical or virtual machine on which it is running. Many of the performance gains in recent versions of Exchange, especially those related to reduction in I/O, are based on highly efficient usage of large amounts of memory. When that memory is no longer available, the expected performance of the system can’t be achieved. For this reason, memory oversubscription or dynamic adjustment of virtual machine memory should be disabled for production Exchange servers.Memory should be sized for guest machines using the same methods as physical deployments. You can find details about memory sizing for Exchange 2010 server roles in Understanding Memory Configurations and Exchange Performance. For additional guidance, see the “Application Considerations” section of a white paper written by the Microsoft Hyper-V team, available for download at Implementing and Configuring Dynamic Memory.

Translation…. Exchange is a jealous beast and wants all the toys to itself. So hyperV and dynamic memory and SBS? Ain’t gonna see it. SQL? Only with the higher up editions of enterprise and datacenter.

3 Thoughts on “So about that dynamic memory and SP1”

Your getting Vmware memory over commit confused with Microsoft dynamic memory. Dynamic memory will never over commit. Now I can’t say how well it works but at least get things straight.

You have to really admit that Microsoft got Hyper V correct from the start which is pretty surprising. It works REALLY well as you yourself have said. I don’t think Microsoft would mess it up by implementing something that would not work. I could be wrong.

Also, what program these days doesn’t want all of the memory it can get ? Even on the desktop. It all comes down to how well behaved the program is and the quality of it’s programming.

All that being said I still believe what I have said in the past. One server program, one virtual machine but that day can’t come until Microsoft changes it’s server OS licensing terms.